On 2/13/2012 10:15 AM, Ulf Zibis wrote:
Interesting issue, especially for us germans!
What is about System.in, if one types some umlaute at Windows console?
System.in is a "InputStream", no charset involved there, you build
your own "reader"
on top of that yourself.
Why are there theoretically different code pages for stdout and stderr?
you can re-direct std err to a log file file but keep the std out to the
console, or re-direct
the std out but keep the std.err to the console, in these scenario, the
stderr and stdout
will use different code page. Basically the approach is that if the
otuput stream gets
re-directed, it keeps using the default charset (with the assumption
that the rest of the
world is using the Windows codepage), if not, use the oem codepage from
the console
on Windows, to make sure the System.out/err outputs the bits that the
underlying
console can understand.
-Sherman
-Sherman
-Ulf
Am 13.02.2012 18:36, schrieb Xueming Shen:
Hi
This is a long standing Windows codepage support issue on Java
platform (we probably have
20 bug/rfes filed for this particular issue and closed as the dup of
4153167). Windows supports
two sets of codepages, ANSI (Windows) codepage and OEM (IBM)
codepage. Windows uses
ANSI/Windows codepage almost "everywhere" except in its dos/command
prompt window,
which uses OEM codepage. For example, on a normal English Windows,
the default Windows
codepage isCp1252 <http://msdn.microsoft.com/en-us/goglobal/cc305145>
(west European Latin) and the OEM codepage used in its dos/command
prompt however is Cp437
<http://msdn.microsoft.com/en-us/goglobal/cc305156> (you can use chcp
command to check/change the "active" codepage
used in your dos/coomand prompt). These two obviously have different
mapping for certain
code points, for example those umlaut characters.
J2SE runtime chooses the ANSI/Windows codepage as its default charset
for its i/o character
reading/writing, graphic text display, etc. including System.out&err.
This causes problem when
the ANSI code page and OEM codepage are not "compatible" and you
happen to need to write
those "in-compatible" characters to the dos/command prompt, as show
in the following test
case
String umlaut = "\u00f6\u00e4\u00fc\u00d6\u00c4\u00dc\u00df";
PrintWriter ps = new PrintWriter(new
OutputStreamWriter(System.out, "Cp437"), true );
ps.println("ps.cp437: " + umlaut);
System.out.println("sys.out : " + umlaut);
System.err.println("sys.err : " + umlaut);
You will see the umlauts get displayed correctly from PrintWriter
with explicit Cp437 encoding
setting, but garbled from system.out and err (because both the
System.out & err use the default
charset Cp1252, which is also used for all necessary Unicode <->
Windows encoding conversion
for that particular vm instance).
For years, we have been debating whether or not we should and how to
fix this issue, do we
want to have two "default charset" for i/o. In jdk6, we have provided
a java.io.Console class
that specifically uses OEM codepage when running on Windows'
dos/command prompt.
However, the feedback is that people still want the System.out/err to
work correctly with
the dos/command prompt, when the OEM codepage used is not
"compatible" with the default
Windows codepage.
The proposed change here is to use OEM codepage for System.out/err
when the vm is
started without its std out/err is redirected to something else, such
as a file (make sure
to only use OME for the dos/command prompt), if vm's std out/err is
redirected, then
continue to use the default charset (file.encoding) for the
System.out/err. I believe this
approach solves the problem without breaking any existing
assumption/use scenario.
The webrev is at
http://cr.openjdk.java.net/~sherman/4153167/webrev
Here is a simple"manual" test case.
public class HelloWorld {
public static void main(String[] args) throws Exception {
String umlaut = "\u00f6\u00e4\u00fc\u00d6\u00c4\u00dc\u00df";
System.out.println("file.encoding =" +
System.getProperty("file.encoding"));
System.out.println("stdout.encoding=" +
System.getProperty("sun.stdout.encoding"));
System.out.println("stderr.encoding=" +
System.getProperty("sun.stderr.encoding"));
System.out.println("-----------------------");
PrintWriter ps = new PrintWriter(new
OutputStreamWriter(System.out, "Cp437"),
true );
ps.println("ps.cp437: " + umlaut);
System.out.println("sys.out : " + umlaut);
System.err.println("sys.err : " + umlaut);
Console con = System.console();
if (con != null)
con.printf("console : %s%n", umlaut);
}
}
-Sherman
